RECENT DEVELOPMENTS IN THE ULTRASONIC PROCESSING OF SEWAGE SLUDGES FOR ENHANCED ANAEROBIC DIGESTION

摘要

'Ultrasound' is the term used to describe sound energy at frequencies above 20kHz. This paper reviews the data collected to date from a 3 year ongoing research programme (funded by 7 water companies/agencies) to develop a large scale ultrasonic processor for the pre-treatment of sewage sludges prior to anaerobic digestion. Results from a number of experiments are presented, including those undertaken at laboratory and pilot scales. The implications of sludge type on the performance of the sonication plant is discussed. Results indicate that the sonication of secondary and digested sludges can produce significant increases in gas production (ranging between 20 - 40%) with commensurate increases in solids destruction. Based on the results produced to date, a large-scale prototype ultrasonic processor is being constructed for installation and testing on a full-scale anaerobic digester in California.